1. Field of the Invention
This invention relates to an electrically controlled brake of the type which is intended to apply brakes to a shaft or other rotating part in the event of an electrical failure.
The invention is concerned with the type of electrically controlled brake in which two brake arms, each carrying a brake shoe are pivoted at respective ends to a fixed support, their other ends being pivotally secured to a brake control assembly which normally holds the brake "off" but which, on cessation of the electrical supply thereto, moves the brake arms to a position where the brake shoes are firmly held "on". The brake includes a strong spring biasing means which tends to pull the brake "on" but which is normally overcome by an electro-hydraulic or electromagnetic thrustor, provided that the electrical supply to the thrustor is maintained to hold the brake "off". When the supply ceases the spring means apply the brake.
An arrangement as above described is hereinafter referred to as "an electrically controlled brake of the type specified".
2. Description of Prior Art
In order to obtain a standard form of such brake to be adapted for various thrusts and therefore for various braking applications, there have been proposals for obtaining a number of different lever ratios and thus braking thrusts from the brake control assembly.